Polymer webs can be made by extrusion, melt spinning, air laid and wet laid processing, etc. Polymer webs have been shown to be a useful substrate for cell culture and tissue culture applications. See, for example, U.S. 20050095695 and WO2006/094076. Bioreactors currently provide an efficient means to produce industrial chemicals, treat and detoxify wastewater, and produce high value pharmaceuticals, biologicals, and small molecules. Bioreactors are generally categorized into four different types (stirred-tank, airlift, hollow-fiber and fixed bed) and can be operated in batch or continuous modes. Isolated enzymes, catalytic molecules (organic and inorganic), microorganisms, animal cells, or plant cells are normally employed as the functional agents within the bioreactor. The cells or microorganisms are typically cultured in suspension or immobilized on a surface or particle. Cell proliferation, cell density, culture stability, scale up potential, and product yield is highest while cell damage resulting from shear stress is lowest when the cells or microorganisms are immobilized to a surface. Similar operating advantages exist when purified enzymes are tethered to surfaces in a bioreactor. The amount of enzyme required is reduced while the stability of the enzyme and product formation is increased when compared to enzyme activity in solution. In addition, immobilization of the culture/enzyme significantly improves the time and cost of the product separation process.
Given the aforementioned considerations, the most important variable for maximizing the output and reaction rates of a bioreactor under optimized parameters is the mass of productive cells or microorganisms (for culture based bioreactors) or the amount of functional enzyme (for enzyme based bioreactors). These considerations led to the development of fibrous matrices having 3-dimensional structure, high surface to volume ratio, high void space, and low pressure drop, and high mass-transfer efficiency. While currently available fibrillar and hollow-fiber reactors have obtained certain levels of efficiency and performance compared to standard fixed bed reactors, a substantial need remains in the industry for a fibrillar reactor having improved density of catalytic and attachment surfaces within an equivalent reactor footprint.